Equity (Details 4) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Stock options by exercise price range
Options Outstanding (in shares)	2,849
Weighted Average Exercise Price per Share (in dollars per share)	$ 40.77
Average Remaining Contractual Life	5 years 9 months 11 days
Options Exercisable (in shares)	2,079
Weighted Average Exercise Price Per Share (in dollars per share)	$ 33.71
Share options, aggregate intrinsic value
Options outstanding aggregate intrinsic value	$ 79	$ 87
Options outstanding average remaining contractual life	5 years 9 months 18 days	6 years
Stock options exercisable aggregate intrinsic value	$ 72	$ 71
Stock options exercisable average remaining contractual life	4 years 9 months 18 days	4 years 10 months 24 days
$24.70 to 27.30
Stock options by exercise price range
Exercise prices, low end of range (in dollars per share)	$ 24.70
Exercise prices, high end of range (in dollars per share)	$ 27.30
Options Outstanding (in shares)	557
Weighted Average Exercise Price per Share (in dollars per share)	$ 25.47
Average Remaining Contractual Life	3 years 2 months 19 days
Options Exercisable (in shares)	557
Weighted Average Exercise Price Per Share (in dollars per share)	$ 25.47
$27.31 to 29.90
Stock options by exercise price range
Exercise prices, low end of range (in dollars per share)	$ 27.31
Exercise prices, high end of range (in dollars per share)	$ 29.90
Options Outstanding (in shares)	465
Weighted Average Exercise Price per Share (in dollars per share)	$ 29.00
Average Remaining Contractual Life	6 years 25 days
Options Exercisable (in shares)	465
Weighted Average Exercise Price Per Share (in dollars per share)	$ 29.00
$32.51 to 35.10
Stock options by exercise price range
Exercise prices, low end of range (in dollars per share)	$ 32.51
Exercise prices, high end of range (in dollars per share)	$ 35.10
Options Outstanding (in shares)	676
Weighted Average Exercise Price per Share (in dollars per share)	$ 34.04
Average Remaining Contractual Life	3 years 8 months 5 days
Options Exercisable (in shares)	676
Weighted Average Exercise Price Per Share (in dollars per share)	$ 34.04
$45.51 to 53.30
Stock options by exercise price range
Exercise prices, low end of range (in dollars per share)	$ 45.51
Exercise prices, high end of range (in dollars per share)	$ 53.30
Options Outstanding (in shares)	357
Weighted Average Exercise Price per Share (in dollars per share)	$ 47.96
Average Remaining Contractual Life	7 years 1 month 10 days
Options Exercisable (in shares)	239
Weighted Average Exercise Price Per Share (in dollars per share)	$ 47.96
$55.91 to 58.50
Stock options by exercise price range
Exercise prices, low end of range (in dollars per share)	$ 55.91
Exercise prices, high end of range (in dollars per share)	$ 58.50
Options Outstanding (in shares)	405
Weighted Average Exercise Price per Share (in dollars per share)	$ 55.95
Average Remaining Contractual Life	8 years 1 month 10 days
Options Exercisable (in shares)	142
Weighted Average Exercise Price Per Share (in dollars per share)	$ 55.95
$63.71 to 66.26
Stock options by exercise price range
Exercise prices, low end of range (in dollars per share)	$ 63.71
Exercise prices, high end of range (in dollars per share)	$ 66.26
Options Outstanding (in shares)	389
Weighted Average Exercise Price per Share (in dollars per share)	$ 66.07
Average Remaining Contractual Life	9 years 1 month 6 days